Project Summary /Abstract The overarching goal of this project is to identify the cognitive mechanisms and neural structures that underlie the decline in executive functioning observed in aging. Several research groups, including ours, have documented age-associated decline in executive functioning and its significant impact on daily functioning. The underlying causes of this decline remain unclear, however; a clearer understanding of how various cognitive and neural changes interact to produce executive decline is needed. We propose an overarching model in which age-associated frontal atrophy, frontal hypoperfusion, and loss of white matter integrity interact to affect information processing speed and executive function. We propose to prospectively study 150 normal elderly with structural neuroimaging, perfusion, and cognitive measures at baseline and again after 36 months. We have three specific aims: 1) test the relationships between age, frontal lobe structure, frontal perfusion, white matter, and cognition cross-sectionally; 2) identify potential health and lifestyle predictors of MRI and cognitive outcomes; and 3) test the relationships between longitudinal change in MRI and longitudinal changes in cognition. This project takes advantage of newly developed techniques of high field, high resolution MRI and cognitive psychology methods of measuring processing speed and executive functioning. We are particularly focusing on white matter integrity because it may be influenced by lifestyle and health issues that are potentially treatable.